The MAXI mission on the ISS: Science and instruments for monitoring All-sky X-ray Images

Masaru Matsuoka*, Kazuyoshi Kawasaki, Shiro Ueno, Hiroshi Tomida, Mitsuhiro Kohama, Motoko Suzuki, Yasuki Adachi, Masaki Ishikawa, Tatehiro Mihara, Mutsumi Sugizaki, Naoki Isobe, Yujin Nakagawa, Hiroshi Tsunemi, Emi Miyata, Nobuyuki Kawai, Jun Kataoka, Mikio Morii, Atsumasa Yoshida, Hitoshi Negoro, Motoki NakajimaYoshihiro Ueda, Hirotaka Chujo, Kazutaka Yamaoka, Osamu Yamazaki, Satoshi Nakahira, Tetsuya You, Ryoji Ishiwata, Sho Miyoshi, Satoshi Eguchi, Kazuo Hiroi, Haruyoshi Katayama, Ken Ebisawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

602 Citations (Scopus)


The Monitor of All-sky X-ray Image (MAXI) mission is the first astronomical payload to be installed on the Japanese Experiment Module - Exposed Facility (JEM-EF or Kibo-EF) on the International Space Station. It has two types of X-ray slit cameras with wide FOVs and two kinds of X-ray detectors consisting of gas proportional counters covering the energy range of 2 to 30 keV and X-ray CCDs covering the energy range of 0.5 to 12 keV. MAXI will be more powerful than any previous X-ray All Sky Monitor payloads, being able to monitor hundreds of Active Galactic Nuclei. A realistic simulation under optimal observation conditions suggests that MAXI will provide all-sky images of X-ray sources of ∼20 mCrab (∼7 × 10-10ergcm-2s-1 in the energy band of 2-30 keV) from observations during one ISS orbit (90 min), ∼4.5 mCrab for one day, and ∼2 mCrab for one week. The final detectability of MAXI could be ∼0.2 mCrab for two years, which is comparable to the source confusion limit of the MAXI field of view (FOV). The MAXI objectives are: (1) to alert the community to X-ray novae and transient X-ray sources, (2) to monitor long-term variabilities of X-ray sources, (3) to stimulate multi-wavelength observations of variable objects, (4) to create unbiased X-ray source cataloges, and (5) to observe diffuse cosmic X-ray emissions, especially with better energy resolution for soft X-rays down to 0.5 keV.

Original languageEnglish
Pages (from-to)999-1010
Number of pages12
JournalPublications of the Astronomical Society of Japan
Issue number5
Publication statusPublished - 2009


  • Catalogs: X-ray source catalogue
  • Instrumentation: All Sky Monitor (ASM)
  • Stars: X-ray novae
  • Stars: X-ray transients
  • X-ray: AGN
  • X-ray: GRB

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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